Structured phosphors for dynamic lighting

ABSTRACT

A structured phosphor device includes a frame member that includes wall regions separating multiple openings of window regions. Further, the structured phosphor device includes a phosphor material filled in each of the multiple openings with a first surface thereof being exposed to an excitation light from one or more laser sources to generate an emitted light out of each window region. Additionally, the structured phosphor device includes an anti-reflective film overlying the first surface of the phosphor material. Furthermore, the structured phosphor device includes a substrate attached to a second surface of the phosphor material in each of the multiple openings. Alternatively, the structured phosphor device includes an array of phosphor pixels dividing a plate of single-crystalline or poly-crystalline phosphor material separated by optically reflective and thermally conductive walls. A dynamic lighting system based on the arrays of phosphor pixels for single or full color image projection is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/740,266, filed Jan. 10, 2020, now U.S. Pat. No. 10,809,606, which isa continuation of U.S. application Ser. No. 15/949,608, filed Apr. 10,2018, now U.S. Pat. No. 10,551,728, the entire contents of which areincorporated herein by reference in their entirety for all purposes.

BACKGROUND

Recently, static and dynamic lighting systems based on laser sources andpumped phosphors are receiving attention as power sources and displaydevices due to availability of power efficient laser pumping sources andconversion phosphors. The static lighting system includes a laser sourcethat delivers required illumination and phosphor material that generateswhite or colored light. The dynamic lighting system of this typeincludes the similar laser source and the optical scanner that directsthe excitation light to the phosphor material to create desired imagesor a full monochromatic or color projection display. The dynamiclighting system also can control not only the position of emitted light,but also its duration, repetition rate and intensity.

Compared with conventional lighting systems including those that arelight emitting diode based, the laser-based and phosphor-pumped lightingsource is characterized by very high beam quality with very low beamdivergence. Using these laser-based and phosphor-pumped lighting sourceswith higher power, efficiency, and coherence, high quality images can beformed. The challenge with these laser-based and phosphor-pumpedlighting systems is lateral spreading of emitted light in the phosphormaterial or device that leads to diffuse spots or crosstalk betweenadjacent pixels in the projection display devices.

Although useful, the pumped phosphor material or devices still havelimitations in application for display and thermal degradation that aredesirable to overcome in accordance to the following disclosure.

SUMMARY

The present invention provides a structured phosphor device andfabrication methods thereof. Particularly, the invention provides anarray of pixelated phosphor devices for independently emitting whitecolored electromagnetic radiation using laser diode excitation sourcesbased on gallium and nitrogen containing materials. Methods forfabricating the structured phosphor devices and architectures of dynamiclighting systems for color projection displays using the structuredphosphors are illustrated that substantially obviate one or more of theproblems due to limitations and disadvantages of the related art.

In an embodiment, the present disclosure provides a structured phosphordevice. The structured phosphor device includes a phosphor configuredfor laser excitation. The phosphor includes an array of pixel regionsseparated by boundary regions. One or more pixel regions of the array ofpixel regions are designed to be addressed by a laser light beamincident through a first surface of the phosphor into phosphor materialthereof and generate at least a partially converted light emission fromthe phosphor material. The boundary regions are configured to limit thecross-talk of the laser light beam between the one or more addressedpixel regions and adjacent pixel regions. The structured phosphor devicefurther includes a surface treatment applied to the first surface of thephosphor. Additionally, the structured phosphor includes a substrateattached to a second surface of the phosphor.

In another embodiment, the present disclosure provides a structuredphosphor device. The structured phosphor device includes a frame memberincluding wall regions separating multiple openings of window regions.The structured phosphor device further includes a phosphor materialfilled in each of the multiple openings with a first surface thereofbeing exposed to an excitation light from one or more laser sources togenerate an emitted light out of each window region. Additionally, thestructured phosphor device includes a surface treatment applied to thefirst surface of the phosphor material. Furthermore, the structuredphosphor device includes a substrate attached to a second surface of thephosphor material and wall regions.

In yet another embodiment, the present disclosure provides a pixelatedphosphor device. The pixelated phosphor device includes a plate ofphosphor material configured to an array of pixels being mutuallyseparated by a thin wall. The pixelated phosphor device further includesa first optical layer overlying a first surface of the plate of phosphormaterial which is subjected to an excitation light beam for inducing anemitted light beam out of each of the array of pixels. Additionally, thepixelated phosphor device includes a second optical layer overlying asecond surface of the plate of phosphor material. The second surface isopposed to the first surface. Furthermore, the pixelated phosphor deviceincludes a substrate attached to the second optical layer.

In still another embodiment, the present disclosure provides a method ofprojecting an image out of a pixelated phosphor. The method includesproviding a pixelated phosphor including an array of pixel regionsseparated by boundary regions. The method further includes attaching asubstrate via a bonding layer to a second surface of the pixelatedphosphor. Additionally, the method includes disposing at least one laserdevice based on Ga and N material to generate a laser light. The methodalso includes modulating and guiding the laser light to the firstsurface of the pixelated phosphor as an incident light beam toindividually excite each of the array of pixel regions of the pixelatedphosphor to generate an emitted light beam. The boundary regions areconfigured to limit cross-talk of the incident light beam acrossneighboring pixel regions. Moreover, the method includes combining allemitted light beams from the array of pixel regions of the pixelatedphosphor to project an image of at least one color per scan cycle.

In yet still another embodiment, the present disclosure provides amethod of forming a structured phosphor device. The method includesproviding a plate of phosphor material of a thickness and attaching asubstrate via a bonding layer to a second surface of the plate ofphosphor material. The method further includes patterning the plate ofphosphor material to define an array of unit regions bounded by wallregions. Additionally, the method includes removing the phosphormaterial in the wall regions through the thickness of the plate ofphosphor material to form trenches separating an array of phosphorpixels in the array of unit regions. The method also includes coatingside walls of the trenches with an optically reflective film.Furthermore, the method includes filling the trenches with a thermallyconductive material to form a wall separating each phosphor pixel fromits neighboring phosphor pixels. Moreover, the method includes treatinga surface layer overlying a first surface of the array of phosphorpixels.

In an alternative embodiment, the present disclosure provides a dynamiclighting system for image projection display. The dynamic lightingsystem includes a laser diode device, characterized by a wavelength. Thedynamic lighting system further includes a lens coupled to an outputbeam of the laser diode device and a scanning mirror device operablycoupled to the output beam of the laser diode device. Additionally, thedynamic lighting system includes a structured phosphor device describedherein containing multiple phosphor pixels coupled to the scanningmirror device and configured to be addressed and excited by the outputbeam to produce an emitted beam of one color. Furthermore, the dynamiclighting system includes an image subsystem for generating an imagebased on the emitted beams of one color respectively from at least aportion of the multiple phosphor pixels selected by beam modulation andmovement of the scanning mirror device.

In another alternative embodiment, the present disclosure provides adynamic lighting system for image projection display. The dynamiclighting system includes a laser diode device, characterized by awavelength and modulated light intensities, and includes a lens coupledto an output beam of the laser diode device. The dynamic lighting systemfurther includes a scanning mirror device operably coupled to the outputbeam of the laser diode device. Additionally, the dynamic lightingsystem includes a first structured phosphor device described hereincontaining multiple first phosphor pixels coupled to the scanning mirrordevice and configured to be addressed and excited by the output beam toproduce a first emitted beam of a first color. The dynamic lightingsystem further includes a second structured phosphor device describedherein containing multiple second phosphor pixels coupled to the firststructured phosphor device and configured to be addressed and excited bythe output beam to produce a second emitted beam of a second color.Furthermore, the dynamic lighting system includes a third structuredphosphor device described herein containing multiple third phosphorpixels coupled to the second structured phosphor device and configuredto be addressed and excited by the output beam to produce a thirdemitted beam of a third color. The dynamic lighting system also includesa first two-state mirror coupled to the scanning mirror to guide theoutput beam to a selected one of the multiple first phosphor pixels atan on-state or pass the output beam at an off-state. Moreover, thedynamic lighting system includes a second two-state mirror coupled tothe first two-state mirror to guide the output beam passed by the firsttwo-state mirror to a selected one of the multiple second phosphorpixels at an on-state or pass the output beam at an off-state. Further,the dynamic lighting system includes a fixed mirror coupled to thesecond two-state mirror to guide the output beam passed by the secondtwo-state mirror to a selected one of the multiple third phosphorpixels. Also, the dynamic lighting system includes an image subsystemfor generating an image based on a combination of the first emittedbeam, the second emitted beam, and the third emitted beam fromrespective one of the multiple first, second, and third phosphor pixelsselected by movements of the scanning mirror device, the first two-statemirror, the second two-state mirror, and the fixed mirror in certaincontrolled rates.

In yet another alternative embodiment, the present disclosure provides adynamic lighting system for image projection display. The dynamiclighting system includes three laser diode devices characterized bythree wavelengths and modulated light intensities, and includes threelenses coupled respectively to three modulated output beams of the threelaser diode devices. The dynamic lighting system further includes threescanning mirror devices operably coupled to the three modulated outputbeams respectively. Additionally, the dynamic lighting system includesthree structured phosphor devices described herein respectivelyincluding multiple phosphor pixels of three colors. The three structuredphosphor devices are coupled to three scanning mirror devices andconfigured to be individually addressed and excited respectively by thethree modulated output beams to produce emitted beams of three colors.Furthermore, the dynamic lighting system includes an image subsystem forgenerating an image based on a combination of the three emitted beams ofthree colors from respective three of multiple phosphor pixels of threecolors selected by movements of the three scanning mirror devices incertain controlled rates.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the latter portions of thespecification and attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded view of a structured phosphor device operatedunder a reflective-mode with perpendicular walls of window framesaccording to an embodiment of the disclosure.

FIG. 1B is a cross-sectional view of the structured phosphor device ofFIG. 1A according to the embodiment of the present disclosure.

FIG. 2 is an exploded view of a structured phosphor device under areflective-mode for a white light emission system architecture with thesloping walls of window frames according to another embodiment of thepresent disclosure.

FIG. 3A is an exploded view of a structured phosphor device operatedunder a transmissive-mode with perpendicular walls of window framesaccording to yet another embodiment of the present disclosure.

FIG. 3B is a cross-sectional view of the structured phosphor device ofFIG. 3A according to the embodiment of the present disclosure.

FIG. 4A is an outline of a method for fabricating a structured phosphordevice with additive processing options according to an embodiment ofthe present disclosure.

FIG. 4B is an outline of a method for fabricating a structured phosphordevice with subtractive processing options according to anotherembodiment of the present invention.

FIGS. 5A through 5F are schematic diagrams for illustrating afabrication method with additive processes for forming an array ofpixelated phosphor devices according to some embodiments of the presentdisclosure.

FIGS. 6A through 6I are schematic diagrams for illustrating afabrication method with subtractive processes for forming an array ofpixelated phosphor devices according to some embodiments of the presentdisclosure.

FIG. 7 is a simplified optical architecture of a single color orwhite-light projection display using one-color pixelated phosphorsexcited by a single laser source according to an embodiment of thepresent disclosure.

FIG. 8 is a simplified optical architecture of a full color projectiondisplay using multi-color pixelated phosphors excited by a single lasersource according to another embodiment of the present disclosure.

FIG. 9 is a simplified optical architecture of a full color projectiondisplay using multi-color pixelated phosphors excited by multiple lasersources according to yet another embodiment of the present disclosure.

DETAILED DESCRIPTION

The present invention provides structured phosphor devices andfabrication methods thereof. Particularly, the invention provides anarray of pixelated phosphor devices for independently emitting whitecolored electromagnetic radiation using a combination of laser diodeexcitation sources based on gallium and nitrogen containing materials.Methods for fabricating the structured phosphor devices andarchitectures of dynamic lighting systems for color projection displaysusing the structured phosphor devices are illustrated that substantiallyobviate one or more of the problems due to limitations and disadvantagesof the related art.

As background, while LED-based light sources offer great advantages overincandescent based sources, there are still challenges and limitationsassociated with LED device physics. The first limitation is the socalled “droop” phenomenon that plagues GaN based LEDs. The droop effectleads to power rollover with increased current density, which forcesLEDs to hit peak external quantum efficiency at very low currentdensities in the 10-200 A/cm² range. Thus, to maximize efficiency of theLED based light source, the current density must be limited to lowvalues where the light output is also limited. The result is low outputpower per unit area of LED die [flux], which forces the use large LEDdie areas to meet the brightness requirements for most applications. Forexample, a typical LED based light bulb will require 3 mm² to 30 mm² ofepi area. A second limitation of LEDs is also related to theirbrightness', more specifically it is related to their spatialbrightness. A conventional high brightness LED emits ˜1 W per mm² of epiarea. With some advances and breakthrough perhaps this can be increasedup to 5-10× to 5-10 W per mm² of epi area. Finally, LEDs fabricated onconventional c-plane GaN suffer from strong internal polarizationfields, which spatially separate the electron and hole wave functionsand lead to poor radiative recombination efficiency. Since thisphenomenon becomes more pronounced in InGaN layers with increased indiumcontent for increased wavelength emission, extending the performance ofUV or blue GaN-based LEDs to the blue-green or green regime has beendifficult.

An exciting new class of solid-state lighting based on laser diodes israpidly emerging. Like an LED, a laser diode is a two-lead semiconductorlight source that that emits electromagnetic radiation. However, unlikethe output from an LED that is primarily spontaneous emission, theoutput of a laser diode is comprised primarily of stimulated emission.The laser diode contains a gain medium that functions to provideemission through the recombination of electron-hole pairs and a cavityregion that functions as a resonator for the emission from the gainmedium. When a suitable voltage is applied to the leads to sufficientlypump the gain medium, the cavity losses are overcome by the gain and thelaser diode reaches the so-called threshold condition, wherein a steepincrease in the light output versus current input characteristic isobserved. At the threshold condition, the carrier density clamps andstimulated emission dominates the emission. Since the droop phenomenonthat plagues LEDs is dependent on carrier density, the clamped carrierdensity within laser diodes provides a solution to the droop challenge.Further, laser diodes emit highly directional and coherent light withorders of magnitude higher spatial brightness than LEDs. For example, acommercially available edge emitting GaN-based laser diode can reliablyproduce about 2 W of power in an aperture that is 15 μm wide by about0.5 μm tall, which equates to over 250,000 W/mm². This spatialbrightness is over 5 orders of magnitude higher than LEDs or put anotherway, 10,000 times brighter than an LED.

In 1960, the laser was demonstrated by Theodore H. Maiman at HughesResearch Laboratories in Malibu. This laser utilized a solid-state flashlamp-pumped synthetic ruby crystal to produce red laser light at 694 nm.Early visible laser technology comprised lamp pumped infrared solidstate lasers with the output wavelength converted to the visible usingspecialty crystals with nonlinear optical properties. For example, agreen lamp pumped solid state laser had 3 stages: electricity powerslamp, lamp excites gain crystal which lases at 1064 nm, 1064 nm goesinto frequency conversion crystal which converts to visible 532 nm. Theresulting green and blue lasers were called “lamped pumped solid statelasers with second harmonic generation” (LPSS with SHG) had wall plugefficiency of ˜1%, and were more efficient than Ar-ion gas lasers, butwere still too inefficient, large, expensive, fragile for broaddeployment outside of specialty scientific and medical applications. Toimprove the efficiency of these visible lasers, high power diode (orsemiconductor) lasers were utilized. These “diode pumped solid statelasers with SHG” (DPSS with SHG) had 3 stages: electricity powers 808 nmdiode laser, 808 nm excites gain crystal, which lases at 1064 nm, 1064nm goes into frequency conversion crystal which converts to visible 532nm. As high power laser diodes evolved and new specialty SHG crystalswere developed, it became possible to directly convert the output of theinfrared diode laser to produce blue and green laser light output. These“directly doubled diode lasers” or SHG diode lasers had 2 stages:electricity powers 1064 nm semiconductor laser, 1064 nm goes intofrequency conversion crystal which converts to visible 532 nm greenlight. These lasers designs are meant to improve the efficiency, costand size compared to DPSS-SHG lasers, but the specialty diodes andcrystals required make this challenging today.

Based on essentially all the pioneering work on GaN LEDs describedabove, visible laser diodes based on GaN technology have rapidly emergedover the past 20 years. Currently the only viable direct blue and greenlaser diode structures are fabricated from the wurtzite AlGaInN materialsystem. The manufacturing of light emitting diodes from GaN relatedmaterials is dominated by the heteroepitaxial growth of GaN on foreignsubstrates such as Si, SiC and sapphire. Laser diode devices operate atsuch high current densities that the crystalline defects associated withheteroepitaxial growth are not acceptable. Because of this, very lowdefect-density, free-standing GaN substrates have become the substrateof choice for GaN laser diode manufacturing. Unfortunately, such bulkGaN substrates are costly and not widely available in large diameters.For example, 2″ diameter is the most common laser-quality bulk GaNc-plane substrate size today with recent progress enabling 4″ diameter,which are still relatively small compared to the 6″ and greaterdiameters that are commercially available for mature substratetechnologies. Further details of the present invention can be foundthroughout the present specification and more particularly below.

Additional benefits are achieved over pre-existing techniques using thepresent invention. In particular, the present invention enables acost-effective white light source and white light and color displays. Ina specific embodiment, the present optical device can be manufactured ina relatively simple and cost effective manner. Depending upon theembodiment, the present apparatus and method can be manufactured usingconventional materials and/or methods according to one of ordinary skillin the art. In some embodiments of this invention the gallium andnitrogen containing laser diode source is based on c-plane galliumnitride material and in other embodiments the laser diode is based onnonpolar or semipolar gallium and nitride material. In one embodimentthe white source is configured from a chip on submount (CoS) with anintegrated phosphor on the submount. In some embodiments the lightsource and phosphor are configured on a common support member whereinthe common support member may be a package member.

In various embodiments, the laser device and phosphor device are mountedon a common support member with or without intermediate submounts andthe phosphor materials are operated in a transmissive mode, a reflectivemode, or a side-pumped mode to result in a laser-based white lightsource. Merely by way of example, the invention can be applied toapplications such as white lighting, white spot lighting, flash lights,automobile headlights, all-terrain vehicle lighting, flash sources suchas camera flashes, light sources used in recreational sports such asbiking, surfing, running, racing, boating, light sources used fordrones, planes, robots, other mobile or robotic applications, safety,counter measures in defense applications, multi-colored lighting,lighting for flat panels, medical, metrology, color or white light beamprojectors and displays, high intensity lamps, spectroscopy,entertainment, theater, music, and concerts, analysis fraud detectionand/or authenticating, tools, water treatment, laser dazzlers,targeting, communications, LiFi, visible light communications (VLC),sensing, detecting, distance detecting, Light Detection And Ranging(LIDAR), transformations, transportations, leveling, curing and otherchemical treatments, heating, cutting and/or ablating, pumping otheroptical devices, other optoelectronic devices and related applications,and source lighting and the like.

Laser diodes are ideal as phosphor excitation sources. With a spatialbrightness (optical intensity per unit area) more than 10,000 timeshigher than conventional LEDs, extreme directionality of the laseremission, and without the droop phenomenon that plagues LEDs, laserdiodes enable characteristics unachievable by LEDs and other lightsources. Specifically, since the laser diodes output beams carrying over1 W, over 5 W, over 10 W, or even over 100 W can be focused to verysmall spot sizes of less than 1 mm in diameter, less than 500 microns indiameter, less than 100 microns in diameter, or even less than 50microns in diameter, power densities of over 1 W/mm², 100 W/mm², or evenover 2,500 W/mm² can be achieved. These power densities are somewhatarbitrary as they do not correspond to combinations of powers anddiameters given above. When this very small and powerful beam of laserexcitation light is incident on a phosphor material or device anextremely bright spot or point source of white light can be achieved.Assuming a phosphor conversion ratio of 200 lumens of emitted whitelight per optical watt of excitation light, a 5 W excitation power couldgenerate 1000 lumens in a beam diameter of 100 microns, or 50 microns,or less. This unprecedented source brightness can be game changing inapplications such as spotlighting or range finding where parabolicreflectors or lensing optics can be combined with the point source tocreate highly collimated white light spots that can travel drasticallylonger distances than ever possible before using LEDs or bulbtechnology.

In one embodiment, the present invention provides a CPoS laser-basedwhite light source comprising a form factor characterized by a length, awidth, and a height. In an example, the height is characterized by adimension of less than 25 mm, and greater than 0.5 mm, although theremay be other variations. In an alternative example, the height ischaracterized by a dimension of less than 12.5 mm, and greater than 0.5mm, although there may be other variations. In yet an alternativeexample, the length and width are characterized by a dimension of lessthan 30 mm, less than 15 mm, or less than 5 mm, although there may beother variations. The apparatus has a support member and at least onegallium-and-nitrogen-containing laser diode devices and phosphormaterial in single device or array of pixelated phosphor devicesoverlying the support member. The laser diode device is capable ofproviding an emission of a laser beam with a wavelength preferably inthe blue region of 425 nm to 475 nm or in the ultra violet or violetregion of 380 nm to 425 nm, but can be other such as in the cyan regionof 475 nm to 510 nm or the green region of 510 nm to 560 nm. In someembodiments, two or more laser diodes or laser stripes are included inthe white light source. In some embodiments, circular beams can be alsoobtained from elliptical beams by optical beam shaping with appropriatelens systems. Combining multiple laser sources can offer many potentialbenefits according to this invention. First, the excitation power can beincreased by beam combining to provide a more powerful excitation sourceand hence produce a brighter light source. Similarly, the reliability ofthe white light source can be increased by using multiple laser sourcesat lower drive conditions to achieve the same excitation power as asingle laser source driven at more harsh conditions such as highercurrent and voltage. A second advantage is the potential for a morecircular spot by rotating the first free space diverging ellipticallaser beam by 90 degrees relative to the second free space divergingelliptical laser beam and overlapping the centered ellipses on thephosphor material or device. Alternatively, a more circular spot can beachieved by rotating the first free space diverging elliptical laserbeam by 180 degrees relative to the second free space divergingelliptical laser beam and off-centered overlapping the ellipses on thephosphor device to increase spot diameter in slow axis divergingdirection. In another configuration, more than 2 laser beams areincluded and some combination of the above described beam shaping spotgeometry shaping is achieved. A third advantage is that multiple coloror wavelength lasers can be included to offer improved performance suchas an improved color rendering or color quality. For example, two ormore blue excitation lasers with slightly detuned wavelengths (e.g. 5 nm10 nm, 15 nm, etc.) can be included to create a larger blue spectrum. Inone embodiment, separate individual laser chips are configured withinthe white light source. By positioning multiple laser chips in apredetermined configuration, multiple excitation beams can be overlappedon the spot on the phosphor device to create a more ideal spot geometry.In alternative embodiments, laser diodes with multiple adjacent laserstripes, i.e., multi-stripe lasers, are included in white light source.The multiple stripes can enable an increased excitation power for abrighter white light source and/or an improved or modified spot patternon the phosphor material. In a preferred embodiment the phosphormaterial can provide a yellowish emission in the 550 nm to 590 nm rangesuch that when mixed with the blue emission of the laser diode a whitelight is produced. In other embodiments, phosphors with red, green,yellow, and even blue emission can be used in combination with the laserdiode excitation source to produce a white light with color mixing.

In an embodiment, a super-luminescent light emitting diode or SLED canbe used as phosphor excitation sources for forming the white lightsource. A SLED is in many ways similar to an edge emitting laser diode;however the emitting facet of the device is designed so as to have avery low reflectivity. A SLED is similar to a laser diode as it is basedon an electrically driven junction that when injected with currentbecomes optically active and generates amplified spontaneous emission(ASE) and gain over a wide range of wavelengths. When the optical outputbecomes dominated by ASE there is a knee in the light output versuscurrent (LI) characteristic wherein the unit of light output becomesdrastically larger per unit of injected current. This knee in the LIcurve resembles the threshold of a laser diode, but is much softer. ASLED would have a layer structure engineered to have a light emittinglayer or layers clad above and below with material of lower opticalindex such that a laterally guided optical mode can be formed. The SLEDwould also be fabricated with features providing lateral opticalconfinement. These lateral confinement features may consist of an etchedridge, with air, vacuum, metal or dielectric material surrounding theridge and providing a low optical-index cladding. The lateralconfinement feature may also be provided by shaping the electricalcontacts such that injected current is confined to a finite region inthe device. In such a “gain guided” structure, dispersion in the opticalindex of the light emitting layer with injected carrier density providesthe optical-index contrast needed to provide lateral confinement of theoptical mode. The emission spectral width is typically substantiallywider (>5 nm) than that of a laser diode and offer advantages withrespect to reduced image distortion in displays, increased eye safety,and enhanced capability in measurement and spectroscopy applications.

SLEDs are designed to have high single pass gain or amplification forthe spontaneous emission generated along the waveguide. The SLED devicewould also be engineered to have a low internal loss, preferably below 1cm⁻¹, however SLEDs can operate with internal losses higher than this.In the ideal case, the emitting facet reflectivity would be zero,however in practical applications a reflectivity of zero is difficult toachieve and the emitting facet reflectivity is designed to be less than1%, less than 0.1%, less than 0.001%, or less than 0.0001% reflectivity.Reducing the emitting facet reflectivity reduces feedback into thedevice cavity, thereby increasing the injected current density at whichthe device will begin to lase. Very low reflectivity emitting facets canbe achieved by a combination of addition of anti-reflection coatings andby angling the emitting facet relative to the SLED cavity such that thesurface normal of the facet and the propagation direction of the guidedmodes are substantially non-parallel. In general, this would mean adeviation of more than 1-2 degrees. In practice, the ideal angle dependsin part on the anti-reflection coating used and the tilt angle must becarefully designed around a null in the reflectivity versus anglerelationship for optimum performance. Tilting of the facet with respectto the propagation direction of the guided modes can be done in anydirection relative to the direction of propagation of the guided modes,though some directions may be easier to fabricate depending on themethod of facet formation. Etched facets provide high flexibility forfacet angle determination. Alternatively, a very common method toachieve an angled output for reduced constructive interference in thecavity would be to curve and/or angle the waveguide with respect to acleaved facet that forms on a pre-determined crystallographic plane inthe semiconductor chip. In this configuration the angle of lightpropagation is off-normal at a specified angle designed for lowreflectivity to the cleaved facet. A low reflectivity facet may also beformed by roughening the emitting facet in such a way that lightextraction is enhanced and coupling of reflected light back into theguided modes is limited. SLEDs are applicable to all embodimentsaccording to the present invention and the device can be usedinterchangeably with laser diode device when applicable.

The white light source typically has a free space with a non-guidedlaser beam characteristic transmitting the emission of the laser beamfrom the laser device to the phosphor material or device. The laser beamspectral width, wavelength, size, shape, intensity, and polarization areconfigured to excite the phosphor material or device. The beam can beconfigured by positioning it at the precise distance from the phosphordevice to exploit the beam divergence properties of the laser diode andachieve the desired spot size. In one embodiment, the incident anglefrom the laser to the phosphor device is optimized to achieve a desiredbeam shape on the phosphor. For example, due to the asymmetry of thelaser aperture and the different divergent angles on the fast and slowaxis of the beam the spot on the phosphor produced from a laser that isconfigured normal to the phosphor would be elliptical in shape,typically with the fast axis diameter being larger than the slow axisdiameter. To compensate this, the laser beam incident angle on thephosphor device can be optimized to stretch the beam in the slow axisdirection such that the beam is more circular on phosphor device. Inalternative embodiments laser diodes with multiple parallel adjacentemitter stripes can be configured to result in a wider and/or morepowerful excitation spot on the phosphor device. By making the spotwider in the lateral direction the spot could become more circular tothe faster divergence angle of the laser emission in the perpendiculardirection. For example, two or more laser stripes may be spaced by 10-30μm, 30-60 μm, 60-100 μm, or 100-300 μm. In some embodiments the parallelstripes have slightly detuned wavelengths for an improved color quality.In other embodiments free space optics such as collimating lenses can beused to shape the beam prior to incidence on the phosphor device. In oneexample, a re-imaging optic is used to reflect and reshape the beam ontothe phosphor device. In an alternative example, the otherwise wastedreflected incident light from the phosphor device is recycled with are-imaging optic by being reflected back to the phosphor device.

In an embodiment, the excitation beam can be characterized by apolarization purity of greater than 50% and less than 100%. As usedherein, the term “polarization purity” means greater than 50% of theemitted electromagnetic radiation is in a substantially similarpolarization state such as the transverse electric (TE) or transversemagnetic (TM) polarization state, but can have other meanings consistentwith ordinary meaning.

In another embodiment, the excitation light beam that incidents on thephosphor has a power of greater than 0.1 W, or greater than 0.1 W, orgreater than 0.5 W, or greater than 1 W, or greater than 5 W, or greaterthan 10 W, or greater than 20 W.

In some embodiments, the phosphor material or device can be operated ina transmissive mode, a reflective mode, or a combination of atransmissive mode and reflective mode, or a side-pumped mode, or othermodes. The phosphor material is characterized by conversion efficiency,a resistance to thermal damage, a resistance to optical damage, athermal quenching characteristic, a porosity to scatter excitationlight, and a thermal conductivity. The phosphor device may have anintentionally roughened surface to increase the light extraction fromthe phosphor material. Optionally, an anti-reflective coating for theemitted light can be applied to improve light extraction from thephosphor material. Although the emitted light from the phosphor materialis a quite broad spectrum and has wide range of emitted angles, theanti-reflective coating is able to allow transmission for majorwavelengths of the emitted light through the coating. In a preferredembodiment the phosphor material is comprised of a yellow emitting YAGmaterial doped with Ce with a conversion efficiency of greater than 100lumens per optical watt, greater than 200 lumens per optical watt, orgreater than 300 lumens per optical watt, and can be a polycrystallineceramic material or a single crystal material. The white light sourcealso has an electrical input interface configured to couple electricalinput power to the laser diode device to generate the laser beam andexcite the phosphor material. The white light source can be configuredto produce greater than 1 lumen, 10 lumens, 100 lumens, 1000 lumens,2000 lumens, or greater of white light output. The support member isconfigured to transport thermal energy from at least one laser diodedevice and the phosphor material to a heat sink. The support member isconfigured to provide thermal impedance of less than 10 degrees Celsiusper watt or less than 5 degrees Celsius per watt of dissipated powercharacterizing a thermal path from the laser device to a heat sink. Thesupport member is comprised of a thermally conductive material such ascopper, copper tungsten, aluminum, alumina, SiC, sapphire, AlN, or othermetals, ceramics, or semiconductors.

In a preferred configuration of this white light source, the commonsupport member comprises the same submount that thegallium-and-nitrogen-containing laser diode chip is directly bonded to.That is, the laser diode chip is mounted down or attached to a submountconfigured from a material such as SiC, AlN, or diamond and the phosphormaterial is also mounted to this submount, such that the submount is thecommon support member. The phosphor material may have an intermediatematerial positioned between the submount and the phosphor. Theintermediate material may be comprised of a thermally conductivematerial such as copper. The laser diode can be attached to a firstsurface of the submount using conventional die attaching techniquesusing solders such as AuSn solder, SAC solder such as SAC305, leadcontaining solder, or indium, or other bonding materials. In analternative embodiment sintered Ag pastes or films can be used for theattach process at the interface. Sintered Ag attach material can bedispensed or deposited using standard processing equipment and cycletemperatures with the added benefit of higher thermal conductivity andimproved electrical conductivity. For example, AuSn has a thermalconductivity of about 50 W/m·K and electrical conductivity of about 16micro-ohm×cm whereas pressureless sintered Ag can have a thermalconductivity of about 125 W/m·K and electrical conductivity of about 4micro-ohm×cm, or pressured sintered Ag can have a thermal conductivityof about 250 W/m·K and electrical conductivity of about 2.5micro-ohm×cm. Due to the extreme change in melt temperature from pasteto sintered form, (260° C.-900° C.), processes can avoid thermal loadrestrictions on downstream processes, allowing completed devices to havevery good and consistent bonds throughout. Similarly, the phosphormaterial may be bonded to the submount using a soldering technique, or asintered Ag technique, but it can be other techniques such as gluingtechnique or metal filled (such as silver) epoxy technique. Typically,thermal interface between the phosphor and the submount and between thesubmount and a heat sink will dominate thermal impedance. The example ofdesirable interface is metallized phosphor with solder bonding twomembers together. Optimizing the bond interface for the lowest thermalimpedance is a key parameter for heat dissipation from the phosphormaterial, which is critical to prevent phosphor degradation and thermalquenching of the phosphor material.

In some embodiments, a phosphor is structured or patterned with multiplephosphor pixel regions and separated by boundary regions. The multiplephosphor pixel regions can be operated in a reflective or transmissivemode to be applied in a dynamic lighting system for single or full colorimage projection displays with the multiple phosphor pixel regions beingindividually addressed by laser excitation with reduced diffusivity andcrosstalk from one pixel to another. Optionally, the multiple phosphorpixel regions are powdered phosphor material filled within an array ofwindow frame structures and later sintered into a solid form.Optionally, the multiple phosphor pixel regions are made by patterningand dividing a plate of single or poly crystalline phosphor materialseparated by the boundary regions. Additionally, the structured orpatterned phosphor device includes an antireflective multilayer film forthe blue and white light formed on a first surface of the phosphorfacing an in-coming excitation radiation from one or more laser sources.Furthermore, for the structured or patterned phosphor operated inreflective mode, the window frame structure or the material for formingthe boundary regions is highly optical reflective and thermallyconductive or at least includes a thermally conductive core coated by ahighly reflective film for specific range of wavelengths, e.g., blue orwhite light. Moreover, a highly reflective multilayer film for blue andwhite light is disposed between a second surface (opposed to the firstsurface) of the phosphor and a substrate. A thermally conductivematerial is used for the substrate. Alternatively, for the structured orpatterned phosphor device in transmissive mode, an antireflective filmfor white light is disposed at the second surface for each of themultiple phosphor pixel regions and a thermally conductive as well asoptically transparent material is used for the substrate.

In some embodiments, the structured phosphor device includes an array ofpixel regions configured with uniform size and shape. Each pixel regionhas a size of less than 1 mm×1 mm, or less than 500 μm×500 μm, or lessthan 250 μm×250 μm, or less than 100 μm×100 μm, or even less than 10μm×10 μm. Optionally, each pixel region has a square shape, arectangular shape, a hexagon shape, or other regular shapes. Optionally,each pixel region contains a phosphor material of a thickness of 100-200μm. Each pixel region is configured to receive an incident light fromlaser excitation from one or more laser sources based on GaN diodes orother laser diodes. The laser excitation is configured to have a powerof at least 0.1 W, or greater than 1 W, or greater than 5 W, or greaterthan 10 W, or greater than 20 W. Optionally, the boundary regions isoptimally made to be substantially small in width to minimize its volumecomparing to that of the multiple pixel regions. Optionally, the widthof the boundary region can be made to be as small as a few microns.

In an alternative embodiment, the structured phosphor device withmultiple phosphor pixels operated in a reflective or transmissive modeare applied for forming a dynamic lighting system with a single (white)color image display, or full color image display with one laser source,or full color image display with multiple laser sources. In one example,a violet laser diode configured to emit a wavelength of 395 nm to 425 nmand excite a first blue structured phosphor device and a second yellowstructured phosphor device. In this configuration, the blue structuredphosphor device is a first blue phosphor plate being structured orpatterned into an array of blue phosphor pixels and the yellowstructured phosphor device is a second yellow phosphor plate beingpatterned into another array of yellow phosphor pixels. Optionally, thefirst blue phosphor plate could be fused or bonded to the second yellowphosphor plate. In a practical configuration the laser beam would bedirectly incident on the first blue phosphor plate wherein a fraction ofthe blue emission would excite the second yellow phosphor plate to emityellow emission to combine with blue emission and generate a whitelight. Additionally, the laser light from the violet laser diode wouldessentially all be absorbed since what may not be absorbed in the bluestructured phosphor device would then be absorbed in the yellowstructured phosphor device. In an alternative configuration the laserbeam would be directly incident on the second yellow structured phosphorplate wherein a fraction of the violet electromagnetic emission would beabsorbed in the second yellow phosphor plate to excite yellow emissionand the remaining violet emission would pass to the first bluestructured phosphor plate and create a blue emission to combine a yellowemission with a blue emission and generate a white light. In analternative embodiment, a powdered mixture of phosphor materials wouldbe disposed onto a transparent plate or into a solid structure using abinder material such that the different colored structured phosphordevices such as blue phosphor plate and yellow phosphor plate areco-mingled and are configured to emit a white light when excited by theviolet laser beam. The powdered mixture phosphor materials could becomprised of YAG based phosphors, LuAG phosphors, and other phosphors.

In a specific embodiment, the structured phosphor device with multiplephosphor pixels operated in a transmissive mode can be configured forlaser excitation from a blue laser diode operating with a wavelength of425 nm to 480 nm. The blue laser light is configured to excite a firstgreen phosphor and a second red phosphor. In this configuration, a firstgreen phosphor plate with multiple green phosphor pixels could be fusedor bonded to the second red phosphor plate with multiple red phosphorpixels. Each pixel can be individually addressed by an incident beam ofthe blue laser light. In a practical configuration the incident beamwould be directly guided to a first addressed pixel of the first greenphosphor plate to emit a green emission while a fraction of the greenemission would be directed to a second addressed pixel the second redphosphor plate to emit a red emission which is combined with the greenemission and a portion of original blue emission to generate a whitelight. In an alternative practical configuration the blue laser lightwould be directly incident on a pixel of the second red phosphor platewherein a fraction of the blue emission would be absorbed in the redphosphor pixel to excite a red emission and a portion of the remainingblue laser emission would pass to a pixel of the green phosphor plateand create a green emission which is combined with the red emission andblue emission to generate a white light. In an alternative embodiment, apowdered mixture of phosphors would be dispensed onto multiple windowregions of a transparent plate and sintered into a solid structure ineach window region using a binder material at certain elevatedtemperatures or pressures such that the different color phosphor pixelssuch as red and green phosphor pixels are co-mingled and are configuredto emit a white light when excited by and combined with the blue laserbeam. The powdered phosphors could be comprised of YAG based phosphors,LuAG phosphors, and other phosphors. The benefit or feature of thisembodiment is the higher color quality that could be achieved from awhite light comprised of red, green, and blue emission. Of course, therecould be other variants of this invention including integrating morethan two phosphors and could include one of or a combination of a redphosphor, green phosphor, blue phosphor, and yellow phosphor.

In several embodiments according to the present invention, the laserbased white light sources is configured as a high CRI white light sourcewith a CRI over 70, over 80, or over 90. In these embodiments, multiplephosphor devices are used in the form of a mixed-power-phosphor-materialcomposition or multiple-phosphor-plates configuration or others.Examples of such multiple phosphor materials or devices include, but arenot limited to YAG, LuAG, red nitrides, aluminates, oxynitrides,CaMgSi₂O₆:Eu²⁺, BAM:Eu²⁺, AlN:Eu²⁺, (Sr,Ca)₃MgSi₂O₈:Eu²⁺, and JEM.

In some configurations of this embodiment the phosphor is attached tothe common support member wherein the common support member may not befully transparent. In this configuration the surface or side of thephosphor where it is attached would have impeded light emission andhence would reduce the overall efficiency or quality of the point sourcewhite light emitter. However, this emission impediment can be minimizedor mitigated to provide a very efficient illumination. In otherconfigurations, the phosphor is supported by an optically transparentmember such that the light is free to emit in all directions from thephosphor point source. In one variation, the phosphor is fullysurrounded in or encapsulated by an optically transparent material suchas a solid material like SiC, diamond, GaN, or other, or a liquidmaterial like water or a more thermally conductive liquid.

In an embodiment, a structured phosphor device in reflective modecontaining an array of pixelated phosphors is shown in FIG. 1A inexploded view. The structured phosphor device 100 is a multilayerstructure with a multi-unit or pixelated configuration formed on asubstrate 110. Optionally, the multi-unit configuration is realized viaa window frame member 130 including multiple window regions 131separated by a wall region (or boundary region) 132. Each of themultiple window regions 131 is filled with a phosphor material 140.Optionally, the multi-unit configuration is realized by dividing asingle plate of phosphor material into array of units. Each unit is aphosphor pixel 140 separated by thin boundary walls 132 of opticallyreflective and thermally conductive material from other neighboringphosphor pixels. Optionally, the device is intended for an applicationto have the phosphor material 140 to be exposed to a laser beam 101illuminated from a laser source (not shown in FIG. 1A). The descriptionof structure or apparatus of using illumination of GaN-based blue laserfor exciting un-patterned phosphor material can be found from U.S. Pat.No. 9,787,963, commonly assigned to Soraa Laser Diode Inc. andincorporated herein by reference. The incident laser beam 101 coupledwith an optical scanning device (not shown) can be guided to individualaddressed phosphor pixels 140 for exciting the phosphor material togenerate an emitted light beam 102 with emission spectra having longerwavelengths than the excitation wavelengths of the incident laser beam101. Optionally, as shown in FIG. 1A, the pixelated phosphor structure100 is reflective in nature such that the emitted light beam 102 isreflected and outputted from a same surface that receives the incidentlaser beam 101.

Optionally, the substrate 110 is made by a highly thermally conductingmaterial for efficiently dissipating heat inside the phosphor material140 generated in the above excitation process to a heat sink (attachedto the substrate 110). Optionally, the substrate 110 is made by amaterial that is also characterized by high optical reflectivity at theexcitation wavelengths of the incident laser beam 101 and over theemission spectra of emitted light beam 102 from the phosphor material140. Optionally, if the substrate 110 does not have high opticalreflectivity at excitation wavelengths and over the emission spectrafrom the phosphor material 140, a highly reflective layer 120 composedof a single film or multilayer structure is included between a secondsurface of the phosphor material 140 surrounded by the wall region 132of the window frame member 130 and a first surface of the substrate 110.

Optionally, the multi-unit configuration of the window frame member 130includes an array of uniformly sized window regions 132 that allows thephosphor material 140 filled therein to form an array of phosphorpixels, each phosphor pixel 140 being capable of independentlygenerating the emitted light beam 102. Collectively, the emitted lightbeams from the array of phosphor pixels 140 are used to display an imagewith increased and controllable resolution for many dynamic displayapplications. In a specific embodiment, the window frame member 130 isconfigured to occupy minimum volume compared with the volume of thearray of phosphor pixels 140. In other words, the wall region 132 of thewindow frame member 130 is made to be substantially thinner relative tothe window regions 131.

The high thermal conductivity of the window frame member 130, combinedwith high thermal conductivity of the substrate 110, helps toefficiently remove heat generated by light absorption in the phosphorpixels 140. The high optical reflectivity at excitation and emissionwavelengths makes minimum amount of light to be lost (absorbed) by thewindow frame member 130 and keeps the light generated in each phosphorpixel 140 not to be spread into adjacent pixels. Thus, the high powerefficiency of each emitted light beam 102 can be maintained, and theoptical crosstalk between pixels is substantially eliminated. In aspecific embodiment, an antireflective coating 150 is disposed on afirst surface of the array of phosphor pixels 140 and wall regions 131of the window frame member 130. The antireflective coating 150 iscomposed of a single film. Optionally, the antireflective coating 150 ismade of a multilayer film including non-absorbing materials withalternating high and low refractive indices. For example, theantireflective coating 150 is made by alternating layers of silicondioxide and titanium pentoxide. Optionally, the antireflective coating150 is configured to allow that both the excitation light (of incidentlaser beam 101) as well as emitted light beam 102 are minimallyreflected from the surface of the phosphor pixels 140. Optionally, theantireflective coating 150 is replaced by a surface layer modified by aroughening treatment on the first surface of the array of phosphorpixels 140. Optionally, a combination of anti-reflective coating andsurface roughening is applied to the first surface of the array ofphosphor pixels 140.

In an embodiment, the shape of each phosphor pixel 140 is depicted insquare shape in FIG. 1A. Optionally, the pixel shape shown in FIG. 1Acan be any shape including rectangle, hexagon, multi-side polygon, andother shapes that are defined by a photolithography process or by adirect laser writing process in a method for fabricating the structuredphosphor device 100. Optionally, the wall regions 131 are substantiallyperpendicular to the surface of the phosphor pixel although sloped wallcan be provided too. More details about the method will be foundthroughout the specification and particularly below.

In another embodiment, the size of each phosphor pixel 140 is definedprimarily by patterning and by etching processes that form the windowregions 131 of window frame member 130 or directly divide a plate ofphosphor material. Optionally, the size of the phosphor pixel can be assmall as 5-10 μm or so depending on applications. The size of the wholepixel array is optionally dependent on the fabrication methodology andoptionally dependent on the size of available plates of phosphormaterial. Optionally, the size of the array of pixelated phosphordevices can vary from few numbers of pixels for low-resolution displayapplication to a full high-resolution array (such as 1024×1920 pixels)for high-resolution full-color display applications. For example, atypical array of pixelated phosphor devices can be an array of 100×100pixels with a square shape pixel size of 100 μm×100 μm and a thicknessin a range of 100 to 200 μm that depends on absorption coefficient ofphosphor material at the excitation wavelengths. Optionally, thepixelated phosphor devices can be formed in other shapes, e.g.,rectangular shape, multi-sides polygon shape, circular shape, ovalshape, etc., with respective ways to measure its size according to itsshape.

FIG. 1B is a cross-sectional view of the structured phosphor device ofFIG. 1A according to the embodiment of the present disclosure. As shown,the structured phosphor device 100 are depicted as an array of phosphorpixels 140 respectively formed in multiple window regions of a windowframe member 130. Each phosphor pixel 140 is one unit of the structuredphosphor devices filled in a window region 131 separated by a wallregion 132 from any neighboring phosphor pixels 140. On a first surfaceof the multiple phosphor pixels 140, an antireflective coating 150 isdisposed to allow that both the excitation light (i.e., incident laserbeam 101) and the emitted light beam 102 are minimally reflected fromthe first surface of each phosphor pixel 140. Optionally, the firstsurface is a top surface of the phosphor in the associated devicepackage. Optionally, the antireflective coating 150 is replaced by asurface layer treated by roughening process on the first surface of eachphosphor pixel 140. Optionally, a combination of anti-reflective coatingand surface roughening is applied to the first surface of each phosphorpixel 140. On a second surface of the multiple phosphor pixels 140, ahighly reflective layer 120 is inserted before the multiple phosphorpixels 140 as well as the window frame member 130 are mounted on asubstrate 110. Optionally, the second surface is a bottom surface of thephosphor in the associated device package. The highly reflective layer120 is configured to substantially reflect mainly the light withwavelengths in a same spectra of incident light beam 101 (primarily bluecolor) and the re-emitted light beam 102 (substantially in white color).The substrate 110 is a highly thermally conductive material designed forefficiently transferring heat in the structured phosphor devices inducedby absorption of the incident laser light beam 101 and excitation forreemitting the light beam 102. Optionally, a mounting thermal pad 160 isadded between a bottom of the substrate 110 and any top surface of adynamic lighting system that is designed to support the structuredphosphor device 100 containing the array of phosphor pixels.

FIG. 2 is an exploded view of structured phosphor devices under areflective-mode for a white light emission system architecture with thesloping walls of window frames according to another embodiment of thepresent disclosure. Referring to FIG. 2, another version of thestructured phosphor device 200 with an array of phosphor pixels 240 inreflective mode is depicted. Compared with the structured phosphordevice 100 shown in FIG. 1A and FIG. 1B, each phosphor pixel 240 of thestructured phosphor device 200 is configured to fit in a window framemember 230 with sloping walls 232 in each window region 231, as opposedto the perpendicular walls 132 in each window region 131 of window framemember 130 used in FIGS. 1A and 1B. As a result of the slopping walls,each phosphor pixel, in one embodiment, appears in an up-down pyramidshape. Of course, each phosphor pixel may be formed in several alternateshapes with multiple slopping walls depending on the frame memberconfiguration. Otherwise, the structure in FIG. 2 is similar tostructured phosphor devices shown in the FIGS. 1A and 1B. Anantireflective coating 250 is placed on a first surface of all phosphorpixels 240 and the window frame member 230. Optionally, theantireflective coating 250 is replaced by a surface layer treated by aroughening treatment on the first surface of all phosphor pixels 240.Optionally, a combination of anti-reflective coating and surfaceroughening is applied to the first surface of all phosphor pixels 240. Areflective layer 220 is inserted between a second surface of allphosphor pixels 240 and a top surface of a substrate 210. The substrate210 is a highly thermally conductive material and is configured to mountvia a bonding layer 260 on a supporting member of a dynamic lightingsystem for color image displays. The window frame member 230 withslopping walls can be made by patterning and wet etching. More detailsabout the method will be found throughout the specification andparticularly below.

FIG. 3A is an exploded view of a structured phosphor device operatedunder a transmissive mode with perpendicular walls of window framesaccording to yet another embodiment of the present disclosure. Referringto FIG. 3A, a transmissive structured phosphor device 300 is a devicewith multilayer structure in a multi-unit configuration fabricated on asubstrate 310. Optionally, the multi-unit configuration is realized viaa window frame member 330 including multiple window regions 331separated by a wall region 332. Each of the multiple window regions 331is filled with a phosphor material forming a phosphor pixel 340.Optionally, the multi-unit configuration is realized by dividing asingle plate of phosphor material into array of units. Each unit is aphosphor pixel 340 separated by thin walls 332 of optically reflectiveand thermally conductive material from other neighboring phosphorpixels.

Referring to FIG. 3A, the structured phosphor device 300 containingarray of phosphor pixels 340 is intended for an application to have atop surface of each phosphor pixel 340 to be independently exposed to anincident laser beam 301 originated from a laser source (not shown inFIG. 3A). The incident laser beam 301 excites each phosphor pixel 340 togenerate a light beam 302 with emission spectra having longerwavelengths than the excitation wavelengths of the incident laser beam101. Optionally, as shown in FIG. 1A, the structured phosphor device 300is operated in transmissive mode such that the emitted light beam 302 isout of a second surface of the phosphor pixel 340. Therefore, thesubstrate 310 must be made by material that is optically transparent aswell as highly thermally conductive. The emitted light beam 302eventually is outputted from the bottom of the substrate 310.

Optionally, the multi-unit configuration of the window frame member 330is formed with an array of uniformly sized window regions 332 thatallows the phosphor material filled therein to form an array of phosphorpixels 340. Each phosphor pixel 340 is capable of independentlygenerating the emitted light beam 302. Collectively, the emitted lightbeams from the array of phosphor pixels 340 are used to display an imagewith increased and controllable resolution for many dynamic displayapplications. In a specific embodiment, the window frame members 330 aresubstantially served as boundaries of phosphor pixels 340 with a minimumvolume compared with the volume of the phosphor material. In otherwords, the wall region 332 of the window frame member 330 is made to besubstantially thinner relative to the window regions 331. Alternatively,each phosphor pixel 340 is formed by dividing a single plate of phosphormaterial with a thin gap/trench that is filled by a wall materialselected from highly thermally conductive and optically reflectivematerial. Optionally, an optical reflective coating can be applied firstto the trench wall before filling the conductive wall material. Again,the wall thickness is minimized for maximizing the phosphor pixels 340in occupancy volume of the pixelated phosphor device 300.

In another embodiment, the size of each phosphor pixel 340 is definedprimarily by etching processes that form the window regions 331 ofwindow frame member 330 or a patterning process that directly divides asingle plate of phosphor material. Optionally, the size of each phosphorpixel 340 can be as small as 5-10 μm or so depending on applications.The size of the whole array of phosphor pixels is optionally dependenton the fabrication methodology for forming the frame member 330.Optionally, the size of the array of phosphor pixels 340 can vary fromfew numbers of pixels for low-resolution display application to a fullhigh-resolution array (such as 1024×1920) for high-resolution full-colordisplay applications. For example, a typical array of pixelated phosphordevices can be an array of 100×100 pixels with a square shape pixel sizeof 100 μm×100 μm separated by a wall of about 5 μm or greater and athickness in a range of 100 to 200 μm that depends on absorptioncoefficient of phosphor material at the excitation wavelengths.Optionally, the pixelated phosphor devices can be formed in othershapes, e.g., rectangular shape, multi-sides polygon shape, circularshape, oval shape, etc., with respective ways to measure its sizeaccording to its shape.

In a specific embodiment, a normally antireflective coating 350 isdisposed on a first surface of the array of phosphor pixels 340 and wallregions 331 of the window frame member 330. The antireflective coating350 is composed of a single film. Optionally, the antireflective coating350 is made of a multilayer film including non-absorbing materials withalternating high and low refractive indices. For example, theantireflective coating 350 is made by alternating layers of silicondioxide and titanium pentoxide. Optionally, the antireflective coating350 is replaced by a surface layer with roughening treatment on thefirst surface of the array of phosphor pixels 340. Optionally, acombination of anti-reflective coating and surface roughening is appliedto the first surface of the array of phosphor pixels 340. In anotherspecific embodiment, an optical transparent layer 320 with optionalanti-reflective coating is placed on top surface of the substrate 310. Amounting pad 360 disposed at the bottom surface of the substrate 310 isalso made by optical transparent material such as optically transparentthermally conductive material for mounting the substrate 310 on to aprojector device of a dynamic lighting system for receiving the emittinglight beam 302 from each phosphor pixel 340 for various dynamic displayapplications.

FIG. 3B is a cross-sectional view of the structured phosphor device ofFIG. 3A according to the embodiment of the present disclosure. As shown,the transmissive structured phosphor device 300 is depicted as multiplephosphor pixels 340 respectively formed in multiple window regions 331of a window frame member 330. Each phosphor pixel 340 is one pixel ofphosphor material filled in a window region (or opening in the framemember) 331 separated by a wall region 332 from any neighboring phosphorpixels 340. On a first surface of the multiple phosphor pixels 340, anantireflective coating 350 is disposed to allow the incident laser beam301 to be minimally (less than 1%) reflected from the first surface ofeach phosphor pixel 340. Optionally, the antireflective coating 350 isreplaced by a surface layer modified by a roughening treatment on thefirst surface of the array of phosphor pixels 340. Optionally, acombination of anti-reflective coating and surface roughening is appliedto the first surface of the array of phosphor pixels 340. On a secondsurface of the multiple phosphor pixels 340, a bonding layer 320 isinserted for mounting the multiple phosphor pixels 340 as well as thewindow frame member 330 on a substrate 310. The bonding layer 320 isselected with a material that is optically transparent (oranti-reflective) to the emission spectra (of light beam 302) of thephosphor material 340 to allow majority of phosphor-emitted light topass through. The bonding layer 320 yet is a strongly reflectivematerial for rejecting >99% original excitation wavelengths (of lightbeam 301). The substrate 310 is a highly thermally conductive materialdesigned for efficiently transferring heat in the structured phosphordevices induced by absorption of the incident laser light beam 101 andexcitation for reemitting the light beam 102. The substrate 310 alsomust be optically transparent for the transmissive structured phosphordevice 300 to allow the emitted light beam 302 to pass through withminimum loss. Optionally, a mounting thermal pad 360 is added between abottom surface of the substrate 310 and a projector device (not shown inFIG. 3B) of a dynamic lighting system that is designed to receive theemitted light for display applications.

In another aspect, the present disclosure provides methods offabricating a structured phosphor device. The fabrications of areflective structured phosphor device and a transmissive structuredphosphor device have lots of similarities and will be outlined below forthe reflective mode only. In an embodiment, FIG. 4A is an outline of anadditive method for fabricating a structured phosphor device withadditive processing options. In another embodiment, FIG. 4B is anoutline of a subtractive method for fabricating a structured phosphordevice with subtractive processing options.

Referring to FIG. 4A, the additive method 400 of fabricating thestructured phosphor device starts by providing a plate of framematerial. Optionally, the plate of frame material is selected from ahighly thermally conductive material. Optionally, the plate of framematerial is also an optically reflective material for wavelengths ofboth incident light beam for exciting a phosphor material associatedwith the structured phosphor devices and output light beam to be emittedfrom the excited phosphor material. Optionally, the process of providingthe plate of frame material includes mounting the plate of framematerial via a bonding layer onto a substrate. Optionally, the bondinglayer is a material with optical reflective characteristics whichprovides substantially full reflection to the light beams withwavelengths of incident light and any re-emitted light from the phosphormaterial. Optionally, the substrate is selected from a material that ishighly thermally conductive and optionally highly optically reflectivefor facilitating dissipation of heat in the phosphor material due toabsorption of excitation light as well as for raising efficiency forgenerating the emitted light and guiding (reflecting) the emitted lightto a projector device of a dynamic lighting system using the structuredphosphor device.

Additionally, the additive method 400 includes patterning the plate offrame material to form an array of window regions separated by wallregions (as boundary of the window regions). Optionally, the framematerial in each window region is removed to form an opening or trenchwith a high height/width aspect ratio into the plate of frame materialwith walls of frame material long the wall regions. Optionally, thewalls are in a substantially perpendicular angle relative to the surfaceof the plate of frame material. Optionally, the opening is formed from afirst (or top) surface of the plate of frame material to a second (orbottom) surface till the bonding layer is exposed. Optionally, the wallsare configured to be minimized in thickness relative to the space ofopening. Optionally, the window regions are patterned with uniform sizeand shape to simplify the manufacture process, although the size andshape can vary, in particular when the patterning is performed byphotolithographic or direct photo writing methods. Optionally, theopening is made with a lateral size ranging from as small as 5 or 10 μmto 100 μm or greater through total thickness of the plate of framematerial in a range of 100 to 200 μm for making functional phosphorpixel therein depending on absorption coefficient of phosphor materialat the excitation wavelengths. Optionally, the opening is made withsloped walls with a relatively larger size on the first surface andreduced sizes into the plate of frame material, making the openingsubstantially in an up-down multi-side pyramid shape. At a bottom of theopening where at least some sloped walls may join, the bonding layer mayor may not be exposed. Optionally, the opening can be formed in manyother shapes, e.g., rectangular shape, multi-sides polygon shape,circular shape, oval shape, etc., with respective ways to measure itssize according to its shape. The shape of each opening determines theshape of a phosphor pixel formed therein. In an example, a structuredphosphor device with small phosphor pixel size of less than 10 μmbounded by a wall thickness down to 5 μm is made into a full array of1024×1920 phosphor pixels for high-resolution full-color displayapplications. Practically, a structured phosphor device with largerphosphor pixel sizes can be made much less costly and still very usefulfor many low-resolution display applications.

Referring to FIG. 4A, the method 400 further includes coating the wallsof the openings with an optically reflecting film. The wall of theopening is part of the frame material which is made by materials thatmay not have sufficient optical reflectivity. Optionally, the opticallyreflecting film applied to the walls is a metalized material that isintended for providing high reflectivity to the excitation light beamand the emitted light beam of the phosphor material to be filled in thearray of window regions. The optically reflecting film also prevents thelight cross-talking between neighboring pixels. With the coating beingapplied, the plate of frame material is thus transformed to be a windowframe member with array of window regions configured for holding aphosphor material.

Furthermore, the method 400 includes filling each opening with aphosphor material. Optionally, the phosphor material is disposed inpowder form with particle sizes in nanometer range to fill each openingof the frame member. Optionally, the phosphor material is disposed within powder form with particle sizes in micro-meter range to fill eachopening of the frame member. Depending on applications, micro-powderphosphor material with larger particle size is chosen over thenano-powder phosphor material with finer particle size for fillinglarger sized openings to form larger phosphor pixels at lower processcost. Optionally, the phosphor material is disposed with a powderedphosphor material mixed with an inorganic binder material to fill thearray of openings. The inorganic binder material is used to facilitate alower temperature sintering process to be performed next. Such inorganicmaterial can enhance the scattering of excitation light in thephosphor-binder material which leads to shorter effective absorptiondistances and thinner phosphor material layers.

Referring to FIG. 4A as the additive process option, the method 400includes sintering the phosphor material in powder form filled in thearray of openings of the frame member to turn the powdered phosphormaterial into hardened phosphor material in a solid form. As a result,an array of phosphor pixels of the structured phosphor device is formedwith the sintered (solid) phosphor material in each opening as aphosphor pixel. Depending on the types, particle sizes, sizecombinations of the powdered phosphor material as well as whether aninorganic binder material is added therein, the sintering process can bevaried in choice of thermal stages design, temperatures and rates ofchange for each stage, pressures applied in each stage, or otherconditions set for each stage. More details of the additive process aredescribed in the specification below.

Referring to FIG. 4B, the method 450 of fabricating the subtractivestructured phosphor device starts by providing a plate of phosphormaterial. Optionally, the plate of phosphor material is selected from asingle-crystal or poly-crystal material. Optionally, the process ofproviding the plate of phosphor material includes mounting (a bottomsurface of) the plate of phosphor material via a bonding layer onto (atop surface of) a substrate. Optionally, the bonding layer is a materialwith optical reflective characteristics which provides substantiallyfull reflection to the light beams with wavelengths of incident lightand any re-emitted light from the phosphor material. Optionally, thesubstrate is selected from a material that is highly thermallyconductive and optionally highly optically reflective for facilitatingdissipation of heat in the phosphor material due to absorption ofexcitation light as well as for raising efficiency for generating theemitted light and guiding (by reflection) the emitted light to aprojector device of a dynamic lighting system using the structuredphosphor devices.

Additionally, the method 450 includes patterning the plate of phosphormaterial to form an array of pixelated phosphors or phosphor pixels. Theprocess of patterning includes certain masking, dry or wet etching, andlifting off steps to form a cross-network of narrow-deep trenches thatdefine the array of phosphor pixels. Optionally, the cross-network ofnarrow-deep trenches can also be formed by directly dicing through theplate of phosphor material. Optionally, the process of patterningincludes photo writing or photo exposing some regions along thenarrow-deep trenches to alter chemical bonding in the crystallizedphosphor material before performing chemical etching to remove thealtered phosphor material in the narrow-deep trenches. Optionally, thearray of phosphor pixels is substantially uniformly sized in length andwidth per pixel and uniformly shaped, although it is not required.Optionally, the size of the whole array of phosphor pixels, i.e., thesize of the structured or pixelated phosphor device, is dependent uponavailable size of a single plate of phosphor material. The thickness ofthe plate of phosphor material limits the depth of each phosphor pixel.Optionally, the depth of the narrow-deep trench reaches the bottomsurface of the plate of phosphor material to expose partially thebonding layer attached to the bottom surface of the plate of phosphormaterial and the top surface of the substrate. The size in length andwidth and the depth of each phosphor pixel also defines its side wall.Optionally, the patterning process can be designed to form the phosphorpixels in many other shapes, e.g., rectangular shape, multi-sidespolygon shape, circular shape, oval shape, etc., with respective ways tomeasure its size according to its shape.

Referring to FIG. 4B, the subtractive method 450 further includescoating walls of the array of phosphor pixels. Unlike the additivemethod 400 where the walls of each window region of the window framemember formed therein are coated, in the subtractive method 450, wallsof each phosphor pixel are coated with a metalized material forproviding high reflective characteristics to prevent the lightcross-talking between neighboring pixels.

Furthermore, the subtractive method 450 includes forming frames forseparating each phosphor pixel from its neighbors. Optionally, a framematerial with high thermal conductivity is selected to be deposited intothe narrow-deep trenches (after the metalized coating is placed).Electroplating is an optional technique for performing the deposition.Optionally, around outer boundaries of the structured phosphor device awall of the frame material is formed to add an outer frame wall for eachphosphor pixel located at the outer boundaries.

FIGS. 5A through 5F are schematic diagrams for illustrating afabrication method with additive processes for forming a structuredphosphor device containing an array of phosphor pixels according to someembodiments of the present disclosure. In some embodiments, the additivefabrication method 400 described in FIG. 4A is shown in more details byFIGS. 5A-5F. Referring to FIG. 5A, the method of fabricating thestructured phosphor device starts with attachment of a plate of framematerial 530 to a substrate 510 via a bonding layer 520. The plate offrame material 530 is provided for being patterned into the window framemember 130 as shown in FIG. 1A. Optionally, the plate of frame materialcan be a silicon material. Optionally, the plate of frame material 530is metalized with a highly reflective film for both excitation light(e.g. blue light from a GaN-based laser source) and phosphor emittedlight (e.g. white or color light with wavelengths longer than theexcitation light). The metalized film of the plate 530 is also turned tobe a good thermal conductor. Optionally, the metalized film is made bytungsten, molybdenum, or other high-melting-point metal materials. Themetalized plate 530 is attached to the substrate 510 as indicated inFIG. 5A. Optionally, the bonding layer 520 between a bottom surface ofthe metalized plate 530 and a top surface of the substrate 510 is alsoan optically reflective layer for both excitation light and phosphoremitted light.

In another step of the additive fabrication method 400 shown in FIG. 5B,a hard mask layer 570 is formed on a surface of the plate 530.Optionally, a deep reactive etching process of the frame material (e.g.of silicon) can be performed to form multiple window regions 535 withperpendicular walls through a whole thickness of the plate of framematerial 530. Each window region 535 in the plate of frame material 530forms a pixel well with vertical walls. Optionally, a wet etchingprocess is performed to form each window region with slope walls in eachside in to the plate of frame material 530. In this case, the pixel wellhas a reversed pyramid shape. Following the etching process, theadditive fabrication method 400 includes a step of stripping the hardmask layer 570 as shown in FIG. 5C.

Optionally, the additive fabrication method 400 includes a step ofcoating a highly reflecting film 580 overlying all side walls and bottomsurfaces inside the pixel wells formed at the window regions 535 afterthe hard mask layer 570 is stripped. This step is depicted in FIG. 5D.Optionally, the reflecting film 580 is designated for efficientlyreflecting both excitation light from the laser source and emitted lightfrom the phosphor material to be added in the pixel wells at the windowregions 535.

The additive method 400 of fabricating pixelated phosphor devicesfurther includes a process, as shown in FIG. 5E, of filling of pixelwells with phosphor material 541. In an embodiment, the phosphormaterial 541 in powder form includes nano-crystalline powders ormicro-crystalline phosphor powders or mixture of phosphor powders withone or more inorganic binder materials that have much lower meltingtemperature than the bulk crystalline/poly-crystalline phosphor itself.When the nano-crystalline powders or micro-crystalline phosphor powdersare used, the melting or sintering temperature of the powders can belowered significantly below the melting temperature of bulk crystallinephosphor material. For example, the melting temperature for YAG phosphormaterials is around 1950° C. Adding inorganic binder material alsofacilitates the next step of sintering the phosphor powder material 541into solid bulk (not fully crystallized) phosphor material 540, as shownin FIG. 5F. The plate of frame material 530 and its metalized film aswell as the reflecting film 580 coated later on the side walls andbottom surfaces of the pixel wells, and top ridges of the of wallregions around each pixel wells that provides the support and patternfor the phosphor powders must survive the sintering temperatures. Byproperly selecting the powder particle sizes of the nano-crystalline ormicro-crystalline phosphor material, it is possible to make thesintering temperatures substantially lower than the bulk meltingtemperature of the phosphor material. In an example, a nominal particlesize of nano-crystalline phosphor powder is approximately below 5 nm andcorrespondingly the sintering temperature used in the sintering process(FIG. 5F) can be reduced to a range of about 600° C. Optionally, thefilling of phosphor powders in the pixel wells can be done by means ofprinting or ink dripping/drying and the sintering of the phosphormaterial in powder form can be programmed with multi-stages of heatingand cooling with different temperatures, pressures, and process times.There can be many variations, modifications, and alternatives.

In an alternative embodiment, the process of turning the phosphor powder541 into bulk phosphor 540 at lower than bulk melting temperature is toemploy laser sintering. The phosphor powders in each pixel well to besintered may be exposed to high temperatures only from very short pulsesof laser light and absorb heat within a local region around the laserspot so that the surrounding structures (wall region of the window framemember 530 and the coating 580, substrate 510, and reflecting films 520)are not damaged or distorted. In such a case, the substrate 510, windowframe member 530 and reflecting films 520 can use materials withrelative low melting temperatures such as silicon, copper, aluminum andothers with much lower cost in easier processes.

Optionally, the additive fabrication method 400 for forming a structuredphosphor device containing an array of phosphor pixels may includepolishing of the surface of sintered phosphor 540 by achemical-mechanical process so that the surfaces of the phosphor pixelsbecome smoother and do not cause excessive light scattering. Optionally,the additive fabrication method 400 further includes coating ananti-reflective film (e.g., anti-reflective film 150 in FIG. 1B oranti-reflective film 250 in FIG. 2) to allow >99% excitation light andat least majority of emitted light to pass through the surface of thesintered phosphor to enhance conversion efficiency of the pixelatedphosphors.

FIGS. 6A through 6I are schematic diagrams for illustrating afabrication method with subtractive processes for forming a structuredphosphor device having an array of pixelated phosphors according to someembodiments of the present disclosure. In some embodiments, thesubtractive fabrication method 450 described in FIG. 4B is shown in moredetails by FIGS. 6A-6I. The subtractive fabrication method isparticularly useful for implementing the formation of array of pixelatedphosphors using a single-crystal phosphor plate that has better thermalperformance than polycrystalline phosphor materials or mixed materialsof phosphor powder and inorganic binder.

Referring to FIG. 6A, the method 450 for fabricating an array ofpixelated phosphors includes providing a plate of single-crystal orpoly-crystal phosphor material 641. Optionally, the plate of phosphormaterial 641 has a thickness in a range of 100 to 200 μm that depends onabsorption coefficient of phosphor material at the excitationwavelengths and a lateral dimension without specific limitation.Optionally, as shown in FIG. 6A, a reflective layer 620 is coated on oneside of the plate of phosphor material 641 in single-crystal orpoly-crystal structure. In the embodiment, the method 450 furtherincludes attaching the reflective layer 620 (which is coated to one sideof the plate of phosphor material 641) to a highly thermally conductingsubstrate 610, as shown in FIG. 6B. Optionally, the substrate 610 ismade of copper. In some embodiments, thermal processing limitations arenot present or are minimized in the subtractive fabrication method 450compared with the additive fabrication method 400 described inparagraphs above.

Referring to FIG. 6C, the method 450 also includes a step for patterningthe plate of phosphor material 641. Optionally, the patterning involvesphoto writing of the single-crystal or poly-crystal phosphor materialwith very high power density, scanned laser beam with nano-second tofemto-second pulse duration. Such a laser writing process can convertthe original (single or poly) crystalline phosphor material 641 within arestricted area into an altered phosphor material that is slightlyporous or amorphous or has at least broken or altered molecular bonds.Optionally, the restricted area is a predefined grid pattern as wallregions 642 dividing the original plate of phosphor material 641 intomultiple unit regions 640. Optionally, the multiple unit regions 640 canbe uniform in size and be configured to be an array of phosphor pixelsor pixelated phosphors. Depending on applications, the size of eachphosphor pixel can be fairly large to obtain a low-resolution whitelight emission plate of a dynamic lighting system for image display orcan be made as small as 5 or 10 μm laterally for forming a fullhigh-resolution display with an array of 1024×1920 phosphor pixels.

Optionally, in order to realize the formation of the multiple phosphorpixels, the method 450 first includes applying a photo-resist mask layer650 to cover all not-to-be patterned unit regions 640, as shown in FIG.6D. Subsequently, the patterned surface is exposed to large area beam offemtosecond or picosecond pulses that alter phosphor material notprotected by the mask.

Then the wall regions 642 with the altered phosphor material can beetched in a wet etching process or in dry plasma etching processselectively because of altered molecular bonding therein, as shown inFIG. 6E. The etch process removes the altered phosphor material in thewall regions 642 to form a network of trenches 643 (only individualtrenches are visible in the cross-sectional view of FIG. 6E). Thesetrenches in phosphor plate can be subsequently filled with lightreflecting and thermally conducting materials. Optionally, once the hardmask 650 was applied, directional, deep reactive ion etching can beapplied to form the trenches 643 directly.

In an example, the photo writing (FIG. 6C) is performed with pulse laserusing ˜100 to 200 fsec pulse duration, repetition rate around 500 kHz,and pulse energies of about 0.2-10 μJ. Pump laser source based on GaNdiode operates at 808 nm and emission from each phosphor pixel occurs at1064 nm. Optionally, multiscan technique is used with linear scanningrates 4-8 mm/sec and pulse energies are selected in a range of about 200nJ.

In an example, the etching process (FIG. 6E) of the altered phosphormaterial in the wall regions 642 is performed with chemical wet etchingof YAG (Er:Y₃Al₅O₁₂) by orthophosphoric acid H₃PO₄ at T>100° C.

Alternatively, the photo-exposure can be done by using reflecting masksplaced over the pixel regions. The repeated exposure of the surfaceswith pulsed light of appropriate spectrum and power density can lead tothe direct removal of the phosphor material therein to form the trenches643.

When hard mask 650 is used (FIG. 6D), the trenches 643 are formed byetching the phosphor material from wall regions 642 that are notprotected by the hard mask 650. Optionally, the trenches 643 are formedto be substantially perpendicular to the surface of the plate ofcrystalline or polycrystalline phosphor material 641. Optionally, thetrenches 643 are made with a depth equal to a thickness of the plate ofphosphor material 641. In other words, the trench 643 is a through-platetrench with a narrow width and deep depth.

In another alternative embodiment, an approach to create the trenches643 in the plate of phosphor material 641 is by mechanical dicingperformed directly along wall regions 642. Optionally, the width oftrenches formed by mechanical dicing can be down to 20-50 μm.Additionally, chipping or cracking in the cross-linked trenches needs tobe avoided. At least, the mechanical dicing provides a way for makingrelatively large phosphor pixels for low resolution display in dynamiclighting system. In contrast, the width of trenches created by photowriting and etching can be made to be smaller than 5 μm, resulting inrelatively small volume loss of the phosphor material while morephosphor material retained for production of emitted light.

Referring to FIG. 6F, the method 450 further includes forming a metalcoating 660 on side walls of the trenches 643. Optionally, the metalcoating 660 is a metal alloy layer. Optionally, the metal coating 660 isa multilayer film, such as depositing an aluminum layer first followedby electroplating compatible seed layer. The metal coating 660 isdesigned for providing function of optical reflection for the emittedlight by the phosphor material in each phosphor pixel 640.

The method 450 further includes a step, shown in FIG. 6G, of strippingthe protective (photo-resist) mask 650 including the portion of metalcoating 660 that deposited thereon. Optionally, the stripping process isa liftoff process that leads to re-appearance of top surface of thephosphor material in each of phosphor pixels 640. At this stage, eachphosphor pixel 640 is still surrounded by the trenches 643 with sidewalls being coated by the metal coating 660. In a next step, the method450 includes filling the trenches 643 (with side walls being coated bymetal coating 660) with highly thermally conducting materials 644 asshown in FIG. 6H. Optionally, copper is one of selected materials tofill the trenches 643 by electroplating. Now, each phosphor pixel 640 isseparated by highly thermally conducting material 644 (as well as metalcoating 660 placed earlier), substantially forming the array ofpixelated phosphors. Optionally, a planarization process may beperformed on the top surface of the whole array of pixelated phosphorsby chemical mechanical polishing for smoothening the surface of phosphorpixels 640 and remove debris of conducting material 644 and metalcoating 660. Optionally, the top surface can be controllably roughenedto increase scattering in the phosphor and effectively increaseabsorption length of the excitation light. The subtractive fabricationmethod 450 may include a step of forming an antireflective film stack670, shown in FIG. 6I, on the top surface of the pixelated phosphorsthat is just smoothened in the previous step for enhancing absorption ofexcitation light and generation of emission light.

In some embodiments, the method 400 and the method 450 are alsoapplicable to fabricate transmissive pixelated phosphors (e.g., seeFIGS. 3A and 3B) with substantially similar processes of fabricatingreflective pixelated phosphors except that the reflective layer 520 or620 attached with the plate of frame material 530 or the plate ofphosphor material 641 should be substituted by a transmissive layer andthe substrate 510 or 610 should be made by optical transparent material.

In an alternative aspect, the present disclosure provides a dynamiclighting system for projection display using a structured phosphordevice. FIG. 7 shows a architecture diagram of a dynamic lighting systemfor one color or black and white projection display using one colorpixelated phosphors excited by a single laser source according to anembodiment of the present disclosure. As shown, the dynamic lightingsystem 700 includes a display medium 740 which is based on a structuredphosphor device containing an array of pixelated phosphors. Among thearray of pixelated phosphors, there is only a single type phosphormaterial designed for generating one color emitted light from conversionof an incident excitation light in the phosphor pixel. Optionally, asshown in FIG. 7, the array of pixelated phosphors 740 is operated intransmissive mode (see FIGS. 3A and 3B). The one incident excitationlight for the pixelated phosphors 740 is a modulated light generated bythe laser diode 710 that is driven by the laser driver, video processingelectronics according to input data represented by the driving controlunit 715. Optionally, the laser diode 710 is a surface mounting laserdevice on a base coupled to a substrate for supporting the structuredphosphor device for directly illuminating the laser light to the topsurface of the pixelated phosphors 740. Optionally, the laser diode 710can be disposed separately from the pixelated phosphors 740 whileguiding the laser light indirectly via an optical fiber (not shown) toilluminate it onto the top surface of the pixelated phosphors 740.Optical elements including at least a lens 720 and a first mirror 730configured as a scanning biaxial, bidirectional mirror and a secondmirror 773 configured as a fixed mirror or optionally a two-state(on-off) mirror. The first mirror 730 provides scanning patterns overthe entire array of pixelated phosphors 740. Typically, the secondmirror 773 is fixed at an on-state to reflect the in-coming modulatedlight to one particular phosphor pixel of the pixelated phosphors 740.Optionally, the second mirror 773 can be an off-state so that thein-coming light is directed completely off the array of pixelatedphosphors 740. This feature can be used as a safety measure when controlof the laser beam or the scanning mirror fails in order to protect theobserver.

The emitted light beams respectively by different phosphor pixels of thepixelated phosphors 740 are processed by an optical imaging subsystem(or simply a projection lens) 750 and directed as an image to the eye ofthe observer or on the screen 795. The array of pixelated phosphors 740provides pixel-level dynamic control of emitted light intensityvariation for displaying a dynamic (yet a single color or black-white)image with a resolution defined by the number of pixels, pixel sizes,and spot size of the excitation beam.

In an alternative embodiment, a full color display architecture can beprovided based on multiple color pixelated phosphors disclosed herein.FIG. 8 shows an architecture of a dynamic lighting system for a fullcolor projection display using a combination of multiple color pixelatedphosphors excited by a single laser source according to anotherembodiment of the present disclosure. Referring to FIG. 8, the dynamiclighting system 800 includes a display medium 840 containing acombination of three structured phosphor devices 841, 842, and 843. Eachstructured phosphor device is an array of pixelated phosphors having onetype of phosphor material configured for emitting a specific color lightconverted from the excitation light. Optionally, one structured phosphordevice 841 is configured to emit a light with substantial green colorspectra, another one structured phosphor device 842 is configured toemit a light with substantial red color spectra, and yet another onestructured phosphor device 843 is configured to emit a light withsubstantial blue color spectra. Optionally, as shown in FIG. 8, thethree structured phosphor devices 841, 842, and 843 are arranged in arow as three large multi-pixels of the structured phosphor device 840.The one incident excitation light for the phosphors is a modulated lightgenerated by the laser diode 810 that is driven by the laser driver,video processing electronics according to input data represented by thedriving control unit 815. A biaxial, bidirectional scanning mirror 830provides scanning patterns over three pixelated phosphors 841, 842, and843. A two-state (on-off) mirror 873 allows the excitation light fromthe laser diode 810 to be guided onto the first pixelated phosphor 843when it is in the on-state. When the mirror 873 is in the off-state andanother mirror 872 is switched into on-state, the excitation light isdirected onto the second pixelated phosphor 842. When both mirror 873and mirror 872 are in the off-state, the excitation light falls onto afixed mirror 880 that brings the light onto the third pixelated phosphor841. Three-colored light emitted respectively by three pixelatedphosphors 841, 842 and 843 is imaged by the optical subsystems 851, 852,and 853 and directed for recombination into one beam by using mirrors861 and 862 and combining cube 860. The images are formed on the eye ofthe observer or on the screen 895.

Additional design and performance flexibility can be achieved by addingadditional light sources and the scanning mirrors to the opticalarchitectures described above. The option with additional opticalelements is of particular interest when the displays or smart lightingare intended for high brightness applications that cannot be satisfiedby the single light source with the highest available power. FIG. 9 is asimplified optical architecture of a full color projection display usingmultiple color pixelated phosphors excited by multiple laser sourcesaccording to yet another embodiment of the present disclosure. Referringto FIG. 9, the optical architecture 900 includes a display medium alsomade by a structured phosphor device 940 with at least three phosphorpixels 941, 942, and 943, which is substantially the same as thestructured phosphor device 840 disclosed in FIG. 8. In this example,back side illumination onto the phosphor pixel is selected for onetypical architecture, even though reflection or front side illuminationcan be used. When higher display brightness than brightness that can beprovided with the highest single laser power output and phosphorcombination is needed, additional laser diodes may be needed. In thisembodiment, three laser diodes 911, 912, and 913 with ultraviolet orblue wavelength may serve as excitation light sources. These laserdiodes are driven with electronic circuits 915, 916, and 917. The laserlight from each of the laser diodes 911, 912, and 913 is collimated withoptical elements 921, 922, and 923 respectively. The collimated,modulated light trains are directed to three biaxial, bidirectionalscanning mirrors 931, 932, and 933 that respectively address thecorresponding three color pixelated phosphors 941, 942, and 943. Thistype of addressing is referred to herein as simultaneous coloraddressing. The data rates to modulate the laser diodes 911, 912, and913 can be at least three times slower than color sequential addressingdata rates disclosed in FIG. 8. Moreover, the scanning mirror resonantfrequencies for the fast axis can be three times lower than thefrequencies required for sequential color addressing of FIG. 8. Threecolor light beams emitted from the three pixelated phosphors 941, 942,and 943 are respectively collected by optical subsystems 951, 952, and953 (similar to those shown in FIG. 8). The superposition of the threecolor light beams is accomplished by right angle static mirrors 961 and963 and cube color combiner 960. The color images or video are thendirected to the screen 995 or directly to the observer.

The foregoing description of the embodiments of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formor to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to explain the principles of the invention and itsbest mode practical application, thereby to enable persons skilled inthe art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to exemplary embodiments of theinvention does not imply a limitation on the invention, and no suchlimitation is to be inferred. The invention is limited only by thespirit and scope of the appended claims. Moreover, these claims mayrefer to use “first”, “second”, etc. following with noun or element.Such terms should be understood as a nomenclature and should not beconstrued as giving the limitation on the number of the elementsmodified by such nomenclature unless specific number has been given. Anyadvantages and benefits described may not apply to all embodiments ofthe invention. It should be appreciated that variations may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims. Moreover, no element and component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the followingclaims.

What is claimed is:
 1. A lighting system comprising: a laser diodedevice configured to generate a laser beam; and a structured phosphordevice configured to emit a light beam upon excitation by the laserbeam, wherein the structured phosphor device includes a phosphorcomprising an array of pixel regions separated by boundary regions,wherein one or more pixel regions of the array of pixel regions areconfigured to be addressed by the laser beam incident on the one or morepixel regions and configured to generate the emitted light beam from thephosphor, wherein the boundary regions are configured to limitcross-talk of the laser beam and the emitted light beam between the oneor more addressed pixel regions and adjacent ones of the array of pixelregions.
 2. The lighting system of claim 1, wherein the emitted lightbeam from the phosphor with or without a portion of the laser beamcreates a substantially white light.
 3. The lighting system of claim 2,wherein the structured phosphor device includes an optically reflectingfilm between a back surface of the phosphor and a substrate to guide thesubstantially white light out of a front surface of the phosphor.
 4. Thelighting system of claim 2, wherein the structured phosphor deviceincludes an anti-reflective film formed between a back surface of thephosphor and a substrate to guide the substantial white light out of theback surface of the phosphor.
 5. The lighting system of claim 1, whereinthe laser diode device includes a gallium and nitrogen containingmaterial, and the laser beam includes a blue wavelength or a violetwavelength.
 6. The lighting system of claim 1, further comprising one ormore scanning mirrors, wherein the laser beam is modulated and guided bythe one or more scanning mirrors to the phosphor for individuallyaddressing the one or more pixel regions in a time period of a scancycle.
 7. The lighting system of claim 1, wherein the structuredphosphor device includes an anti-reflective coating or a surfaceroughening feature or a combination of both overlying a front surface ofthe phosphor.
 8. The lighting system of claim 1, wherein the boundaryregions comprise a conductive material that is optically reflective towavelengths of combined spectra of the laser beam and the emitted lightbeam.
 9. A lighting system comprising: a laser diode device configuredto generate a laser beam; and a structured phosphor device configured toemit a light beam upon excitation by the laser beam, wherein thestructured phosphor device comprises: a frame member comprising wallregions separating multiple openings of window regions; and a phosphormaterial in each of the multiple openings of the window regions, whereina first surface of the phosphor material in at least one of the multipleopenings is exposed to the laser beam to generate the emitted light outof the at least one of the multiple openings.
 10. The lighting system ofclaim 9, wherein the multiple openings of the window regions comprise auniform size and shape, wherein the phosphor material in the multipleopenings forms an array of phosphor pixels with each pixel size havingthe uniform size and shape.
 11. The lighting system of claim 10, whereineach of the array of phosphor pixels has a rectangular or square shapewith the wall regions being substantially vertical or a reversed pyramidshape with the wall regions being sloped.
 12. The lighting system ofclaim 9, wherein the structured phosphor device includes an opticallyreflective layer disposed between the phosphor material and a substrate.13. The lighting system of claim 9, wherein the structured phosphordevice includes an optically transmissive layer disposed between thephosphor material and a substrate.
 14. A lighting system comprising: alaser diode device configured to generate an excitation light beam; anda structured phosphor device configured to emit a light beam uponexcitation by the excitation light beam, wherein the structured phosphordevice comprises: a plate of phosphor material configured in an array ofpixels each mutually separated by a thin wall; a first optical layeroverlying a first surface of the plate of phosphor material, the firstoptical layer configured to receive the excitation light beam andemitting the emitted light beam out of each of the array of pixels; asecond optical layer overlying a second surface of the plate of phosphormaterial, the second surface being opposed to the first surface; and asubstrate coupled to the second optical layer.
 15. The lighting systemof claim 14, wherein the plate of phosphor material comprises asingle-crystalline phosphor or poly-crystalline phosphor.
 16. Thelighting system of claim 14, wherein each pixel of the array of pixelshas a uniform pixel size and pixel shape, and wherein the pixel sizecomprises lateral dimension ranging from a few millimeters to less than100 μm and a depth ranging from 100 μm to 200 μm or greater, and thearray of pixels includes between 100×100 pixels or less to 1024×1920pixels.
 17. The lighting system of claim 14, wherein the thin wallcomprises metalized material with optical reflection characteristics forboth the excitation light beam and the emitted light beam.
 18. Thelighting system of claim 14, wherein the first optical layer comprisesan anti-reflective film characterized for substantially enhancing >99%of the excitation light beam in each of the array of pixels.
 19. Thelighting system of claim 14, wherein the second optical layer comprisesa reflective characteristic for substantially reflecting both theexcitation light beam and the emitted light beam at the second surfaceto guide the emitted light beam out of the first surface of the plate ofphosphor material.
 20. The lighting system of claim 14, wherein thesecond optical layer comprises a transmissive characteristic for passingthe emitted light beam out of the second surface of the phosphormaterial operated in transmissive mode, and wherein the substratecomprises a material being optically transparent at least for theemitted light beam.